Image sensor unit and image reading apparatus using the same

ABSTRACT

An image sensor unit includes: a light source including a light emitting element on a light emitting surface; a light guide that causes light from the light source to be incident on a light incident surface facing to the light emitting surface, ejects the light from a light ejecting surface and illuminates a document; a rod lens array that images reflected light from the document; a sensor substrate on which a photoelectric conversion element is mounted, the photoelectric conversion element converting the reflected light imaged by the rod lens array into an electric signal; and a frame that supports the light source, the light guide, the rod lens array and the sensor substrate, wherein positioning sections are provided on an opposite side of the light emitting surface of the light source and at a part of the frame which is disposed at the opposite side of the light emitting surface.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority of theprior Japanese Patent Application No. 2010-282128, filed on Dec. 17,2010, the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an image sensor unit and an imagereading apparatus using the same. In particular, the present inventionrelates to an image sensor unit capable of accurately positioning alight source with respect to a light guide and an image readingapparatus using the same.

2. Description of the Related Art

Typically, copiers, image scanners and facsimiles are known as imagereading apparatuses. These image reading apparatuses employ a contactimage sensor unit (CIS: Contact Image Sensor) capable of opticallyreading image information of a document and converting the informationinto an electric signal. The contact image sensor unit includes an LEDmodule having a light emitting element, such as LED, for illuminating adocument, and a light guide that guides light emitted from the LEDmodule and performs linear illumination. Typically, the LED module andthe light guide are attached to a frame and are configured into a unit.

The light guide is formed of a transparent member having a lengthcorresponding to the width of a document to be illuminated. In the lightguide, a side end surface is a light incident surface on which lightfrom the LED module incidents, and one surface along the longitudinaldirection is a light ejecting surface for ejecting incident light. Thus,the light emitting element of the LED module is required to be arrangedso as to be faced to the light incident surface of the light guide.However, since the light guide has a narrow shape, the light incidentsurface is smaller in area than the light ejecting surface. Accordingly,in a contact image sensor unit, it is difficult to accurately disposethe light emitting element of the LED module on the light incidentsurface of the light guide. If the light incident surface of the lightguide and the light emitting element are disposed in a manner deviatingfrom each other, the amount of light emitted from the light emittingelement and incident on the light guide decreases, which causes aproblem in that a desired illumination intensity for illuminating thedocument cannot be attained.

Patent Document 1 discloses a line illuminating device in which threepins for positioning a light emitting element are formed at an end of alight guide casing filled with a light guide or on a side end surface ofthe light guide and three holes into which the respective pins areinserted are formed on the light emitting element. Such a lineilluminating device allows the light emitting element to be positionedwith respect to the light guide by inserting the pins on the light guideside into the respective holes of the light emitting element.

Patent Document 1

-   Japanese Laid-Open Patent Publication No. 2004-146870

The line illuminating device of Patent Document 1 is capable ofpositioning the light emitting element with respect to the light guide.However, in a case of changing the size of the light incident surface ofthe light guide or changing the mounting angle of the light guide withrespect to a frame, the positions of the pins formed on the light guideside are changed. Accordingly, there is a problem in that the positionsof holes of the light emitting element and the respective pins on thelight guide side do not match with each other and the light emittingelement cannot be accurately positioned with respect to the light guide.

In the line illuminating device of Patent Document 1, the three pins onthe light guide side should correctly be inserted into the three holeson the light emitting element. This operation is not easy. Accordingly,there is a problem in that assemblage of the image sensor unit requireseffort.

SUMMARY OF THE INVENTION

The present invention is made in view of the aforementioned problems. Itis an object of the present invention to provide an image sensor unitcapable of accurately positioning and easily attaching the light sourcewith respect to the light guide, and an image reading apparatus usingthe same.

An image sensor unit of the present invention includes: a light sourceincluding a light emitting element on a light emitting surface; a lightguide that causes light from the light source to be incident on a lightincident surface facing to the light emitting surface, ejects the lightfrom a light ejecting surface and illuminates an object to beilluminated; an imaging element imaging reflected light from theilluminated object; a sensor substrate on which a photoelectricconversion element is mounted, the photoelectric conversion elementconverting the reflected light imaged by the imaging element into anelectric signal; and a supporter that supports the light source, thelight guide, the imaging element and the sensor substrate, whereinpositioning sections are provided on an opposite side of the lightemitting surface of the light source and at a part of the supporterwhere the opposite side of the light emitting surface of the lightsource is positioned.

An image reading apparatus using an image sensor unit of the presentinvention includes: a light source including a light emitting element ona light emitting surface; a light guide that causes light from the lightsource to be incident on a light incident surface facing to the lightemitting surface, ejects the light from a light ejecting surface andilluminates an object to be illuminated; an imaging element imagingreflected light from the illuminated object; a sensor substrate on whicha photoelectric conversion element is mounted, the photoelectricconversion element converting the reflected light imaged by the imagingelement into an electric signal; and a supporter that supports the lightsource, the light guide, the imaging element and the sensor substrate,wherein positioning sections are provided on an opposite side of thelight emitting surface of the light source and at a part of thesupporter where the opposite side of the light emitting surface of thelight source is positioned.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing an appearance of an image scanner 1of this embodiment;

FIG. 2 is a schematic view showing a configuration in a CIS unit 5 ofthis embodiment;

FIG. 3 is an exploded perspective view of the CIS unit 5 of thisembodiment;

FIG. 4 is an enlarged exploded perspective view of the CIS unit 5 ofthis embodiment;

FIG. 5 is an exploded sectional view of the CIS unit 5 of thisembodiment;

FIG. 6A is a plan view of an LED module 30 of a first embodiment;

FIG. 6B is a perspective view of the LED module 30 of the firstembodiment;

FIG. 7 is a perspective view in which the CIS unit 5 of the firstembodiment is assembled;

FIG. 8A is a plan view of an LED module 30 according to a secondembodiment;

FIG. 8B is a perspective view of the LED module 30 according to thesecond embodiment; and

FIG. 9 is a perspective view in which the CIS unit 5 of the secondembodiment is assembled.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of an image sensor unit and an image readingapparatus using the same according to the present invention willhereinafter be described with reference to drawings. In the drawings,which will be described below, a main scanning direction of the imagesensor unit is denoted by an arrow M, and a sub-scanning direction isdenoted by an arrow S, as necessary.

First, a structure of a flatbed image scanner 1 as an image readingapparatus will be described with reference to FIG. 1. FIG. 1 is aperspective view showing an appearance of the flatbed image scanner 1.As shown in FIG. 1, the image scanner 1 includes a casing 2 and a platencover 3 that is provided in a manner capable of opening and closing withrespect to the casing 2 so as to cover a document.

The casing 2 includes a platen glass 4, a contact image sensor unit(hereinafter, referred to as CIS unit 5), a holder 6, a slide shaft 7, adrive motor 8 and a wire 9. The platen glass 4 is a transparent platemade of a glass as a document stage. The CIS unit 5 optically readsimage information of the document as an illuminated object placed on theplaten glass 4, and converts the information into an electric signal.The detailed configuration of the CIS unit 5 will be described later.The holder 6 holds the CIS unit 5 in a manner surrounding the unit. TheCIS unit 5 held by the holder 6 is driven by the drive motor 8 via thewire 9 and moves in a reading direction (sub-scanning direction) alongthe slide shaft 7.

Next, relationship between configurational elements and an optical pathfrom a light source 10 in the CIS unit 5 will be described withreference to FIG. 2. FIG. 2 is a schematic view showing theconfiguration in the CIS unit 5. In the CIS unit 5, the light source 10,a light guide 11, a rod lens array 12 and a sensor substrate 14 arearranged.

The light source 10 illuminates the document. The light source 10includes, for instance, light emitting elements 10 r, 10 g and 10 bhaving light emitting wavelengths of three colors, or red, green andblue. The light source 10 emits light by sequentially switching thelight emitting elements 10 r, 10 g and 10 b.

The light guide 11 guides the light emitted from the light source 10 tothe document placed on the platen glass 4. The light guide 11 is formedinto a narrow shape having a length corresponding to the width of thedocument. The light guide 11 is formed of transparent plastic, such asacrylic resin or polycarbonate.

A side end surface on one side of the light guide in the longitudinaldirection (main scanning direction) is a light incident surface 11 a onwhich light from the light source 10 is incident. In the CIS unit 5, thelight emitting elements 10 r, 10 g and 10 b of the light source 10 aredisposed facing to the light incident surface 11 a such that the lightfrom the light source 10 is efficiently incident on the light guide 11.A surface of the light guide 11 along the longitudinal direction andfacing to the document on the platen glass 4 is a light ejecting surface11 b from which the incident light on the light guide 11 is ejected. Asurface facing to the light ejecting surface 11 b is a reflectingsurface 11 c that reflects the light from the light incident surface 11a in the light guide 11.

Accordingly, the light guide 11 scatters the incident light from thelight incident surface 11 a at the reflecting surface 11 c, and ejectsthe light from the light ejecting surface 11 b, thereby illuminating thedocument. The light source 10 and the light guide 11 thus function as anilluminating device that illuminates the document.

The rod lens array 12 includes a plurality of erect equal magnificationimaging elements arranged in a direction identical to the longitudinaldirection of the light guide 11. The rod lens array images lightreflected from the document on a photoelectric conversion element 13.

The sensor substrate 14 includes a plurality of photoelectric conversionelements 13, which convert the reflected light imaged by the rod lensarray 12 into an electric signal, arranged in the direction identical tothe longitudinal direction of the light guide 11.

The rod lens array 12 and the photoelectric conversion element 13 areformed into a length corresponding to the width of the document.

When the image scanner 1 including the CIS unit 5 configured asdescribed above reads a document, the image scanner 1 moves the CIS unit5 to a reading start position of the document. The CIS unit 5 moved tothe reading start position sequentially turns on the light emittingelements 10 r, 10 g and 10 b of the light source 10. Light from thelight source 10 is incident on the light incident surface 11 a of thelight guide 11 and subsequently ejected uniformly from the lightejecting surface 11 b. The surface of the document is illuminated withthe light ejected from the light guide 11 linearly along the mainscanning direction. The illuminated light is reflected by the documentand subsequently imaged by the rod lens array 12 on the photoelectricconversion element 13 mounted on the sensor substrate 14. Thephotoelectric conversion element 13 converts the imaged reflected lightinto an electric signal. The CIS unit 5 converts the reflected light ofall the red, green and blue and thus a reading operation on one scanline along the main scanning direction is finished.

Subsequently, the image scanner 1 moves the CIS unit 5 in thesub-scanning direction by as long as one scan line. The CIS unit 5performs the reading operation on one scan line as described above.Thus, the CIS unit 5 repeats moving by one scan line and the readingoperation, thereby allowing the entire document to be read. The imagescanner 1 image-processes the electric signal converted by the CIS unit5 as necessary and stores the signal as image data in a storing unit,and thus the reading of the entire document placed on the platen glass 4is finished.

The CIS unit 5 configured as described above requires that the lightejected from the light guide has a desired illumination intensity. Thus,in the CIS unit 5, the light source 10 is required to be correctlydisposed at a position facing to the light incident surface 11 a of thelight guide 11. The CIS unit 5 of this embodiment is configured so as todispose configurational elements of the CIS unit 5 at respectiveprescribed positions using the frame 20.

A manner of supporting each configurational element of the CIS unit 5 ofthis embodiment by means of the frame 20 will hereinafter be describedbelow.

First Embodiment

First, configurational elements of a CIS unit 5 of a first embodimentwill be described with reference to FIGS. 3 to 5. FIG. 3 is an explodedperspective view of the CIS unit 5. FIG. 4 is an enlarged view of thelight source 10 in the perspective view shown in FIG. 3. FIG. 5 is asectional view of the configurational elements of the CIS unit 5 takenalong the sub-scanning direction.

As shown in FIGS. 3 and 4, the CIS unit 5 of this embodiment includes alight source 10, a light guide 11, a rod lens array 12, a sensorsubstrate 14, and a frame 20 as a supporter that supports theseelements.

The frame 20 has a substantially rectangle shape viewed in the mainscanning direction, and is formed to be elongated along the mainscanning direction. The frame 20 is formed to have convex and concaveshapes in order to support each configurational element of the CIS unit5.

Description will be made more specifically. As shown in FIGS. 4 and 5, alens insertion groove 21 into which the rod lens array 12 is inserted, alight guide supporting groove 22 where the light guide 11 is mounted, asubstrate installation part 23 (see FIG. 5) where the sensor substrate14 is installed, and a light source mount 24(see FIG. 4) where the lightsource 10 is mounted, are formed in the frame 20.

The lens insertion groove 21 is formed along the longitudinal directionof the frame 20 in a manner of having an opening at the top of the frame20. As shown in FIG. 5, the lens insertion groove 21 also has an openingat the bottom to be formed such that reflected light from the documentis ejected below through the rod lens array 12 so as to be imaged on thephotoelectric conversion element 13.

The light guide supporting groove 22 is formed in parallel to the lensinsertion groove 21. As shown in FIG. 5, the light guide supportinggroove 22 is formed to have an opening 22 a along the longitudinaldirection such that the light guide 11 can be inserted fromsubstantially above the frame 20. Above the light guide supportinggroove 22, a holding overhang 22 b is formed integrally with the frame20. The holding overhang 22 b detachably holds the light guide 11inserted into the light guide supporting groove 22. FIG. 5 indicates thelight guide 11 held in the light guide supporting groove 22 by a chaindouble-dashed line. As shown in FIG. 5, the light guide supportinggroove 22 is formed so as to have a sectional shape substantiallyidentical to a sectional shape of the light guide 11 except for thelight ejecting surface 11 b. Accordingly, the light guide 11 can bepositioned at a prescribed mounting angle. In a state where the lightguide 11 is held in the light guide supporting groove 22, the documentis illuminated with the light ejected from the light ejecting surface 11b of the light guide 11 at an angle according to the mounting angle (seean arrow A in FIG. 5).

As shown in FIG. 4, a convex longitudinal positioning section 11 d isintegrally formed with the light guide 11 of this embodiment at an endon a side of the light incident surface 11 a of opposite ends in thelongitudinal direction. The convex longitudinal positioning section 11 dis formed to protrude from a side surface adjacent to the light incidentsurface 11 a in a direction orthogonal to the longitudinal direction ofthe light guide 11. On the other hand, the light guide supporting groove22 includes a concave longitudinal positioning section 22 c formed to befitted with the convex longitudinal positioning section 11 d, at an endon a side of the light source in the longitudinal direction.Accordingly, the concave longitudinal positioning section 22 c is fittedwith the convex longitudinal positioning section 11 d, thereby allowingthe light guide 11 to be positioned with respect to the longitudinaldirection of the light guide supporting groove 22. There is a case ofexpansion and contraction of the light guide 11 in the longitudinaldirection due to a thermal effect. Even in this case, the position ofthe longitudinal positioning section 11 d of the light guide 11 does notchange but only the end opposite to the light incident surface 11 a isdeviated in the longitudinal direction. Accordingly, even when the lightguide 11 expands and contracts in the longitudinal direction, theposition of the light incident surface 11 a adjacent to the longitudinalpositioning section 11 d does not change with respect to the frame 20.

As shown in FIG. 5, the substrate installation part 23 is formed in abottom peripheral part of the frame 20 into a shape cut upwardly by onestage from the bottom surface of the frame 20. The sensor substrate 14is installed to the substrate installation part 23 from the bottom. In astate where the sensor substrate 14 is installed to the substrateinstallation part 23, the rod lens array 12 is disposed above thephotoelectric conversion element 13 mounted on the sensor substrate 14.

As shown in FIG. 4, the light source mount 24 is formed at a position atone end of the frame 20 in the longitudinal direction and facing to thelight incident surface 11 a of the light guide 11 mounted in the frame20. At the light source mount 24, a light source insertion groove 25,into which the light source 10 can be inserted from the bottom, isformed. The light source insertion groove 25 is formed so as tovertically penetrate the frame 20.

Here, the light source 10 to be inserted into the light source insertiongroove 25 is described with reference to FIGS. 6A and 6B. FIG. 6Aincludes diagrams showing plan and rear elevational views and plan viewof the light source. FIG. 6B shows a perspective view of the lightsource.

The light source 10 of this embodiment is an LED module 30 includingLEDs as light emitting elements emitting red, green and blue lightrespectively. The LED module 30 includes a main body 31 and four leadterminals 38 protruding from the main body 31. As shown in FIG. 6A, themain body 31 is formed into a flat board shape having a width W and athickness T.

The light emitting surface 32 of the main body 31 is formed flatly; LEDs33 r, 33 g and 33 b having light emitting wavelengths of three colors,or red, green and blue, are arranged thereon in a state where thesurfaces are protected by, for instance, transparent resin. The LEDs 33r, 33 g and 33 b are disposed in a manner deviated from the center line(alternate long and short dashed line shown in FIG. 6A) of the main body31 to one side in the width direction.

On the other hand, on a back surface 34 opposite to the light emittingsurface 32 of the main body 31, a convex positioning section 35protruding from the back surface 34 is formed linearly along the entirelength of the main body 31 in the vertical direction. The positioningsection 35 is formed at a position deviated from the center line of themain body 31 to the other side in the width direction. Accordingly, theLEDs 33 r, 33 g and 33 b and the positioning section 35 are arranged onopposite sides with respect to the center line of the main body 31 andon the opposite surfaces. On both sides of a top surface 36 of the mainbody 31 in the width direction, insertion positioning surfaces 37, whichare flat and lower than the top surface 36, are formed. As describedabove, the LEDs 33 r, 33 g and 33 b and the positioning section 35 arethus disposed on the opposite side with respect to the center line.Accordingly, the main body 31 is not thick at a part on which LEDs 33 r,33 g and 33 b are arranged, thereby allowing heat radiation of the LEDs33 r, 33 g and 33 b to be improved. Note that, not limited to this case,the LEDs 33 r, 33 g and 33 b and the convex positioning section 35 mayoverlap with each other in the thickness direction of the main body 31.

As shown in FIG. 4, the aforementioned light source insertion groove 25of the frame 20 is formed into a shape into which the LED module 30 canbe inserted in a state where the width direction of the LED module 30 isdisposed along the sub-scanning direction. In the state where the LEDmodule 30 is inserted into the light source insertion groove 25, thelight incident surface 11 a of the light guide 11 and the LEDs 33 r, 33g and 33 b of the LED module 30 are required to be disposed in place atpositions facing to each other. Thus, in this embodiment, as shown inFIG. 4, a concave positioning section 26 corresponding to the convexpositioning section 35 formed on the back surface 34 of the LED module30 is formed in the light source insertion groove 25. That is, theconcave positioning section 26 is formed on the surface of the lightsource insertion groove 25 facing to the back surface 34 of the LEDmodule 30. The concave positioning section 26 is formed linearly alongthe entire length of the light source insertion groove 25 in thevertical direction.

In the state where the LED module 30 is inserted into the light sourceinsertion groove 25, the convex positioning section 35 and the concavepositioning section 26 position the LED module 30 with respect to thelight source insertion groove 25. More specifically, the convexpositioning section 35 and the concave positioning section 26 are convexand concave in a direction orthogonal to the width direction of the LEDmodule 30. Accordingly, the LED module 30 is positioned with respect tothe width direction of the light source insertion groove 25.

On both sides in the longitudinal direction and the top of the lightsource insertion groove 25, an insertion positioning section 27 coveredwith the top surface of the frame 20 is formed. The insertionpositioning section 27 comes into contact with the insertion positioningsurface 37 of the LED module 30 inserted into the light source insertiongroove 25, thereby allowing the LED module 30 to be positioned withrespect to the light source insertion groove 25 in the verticaldirection.

The LED module 30 is thus arranged in place at a certain position withrespect to the frame 20 by means of the convex positioning section 35and the concave positioning section 26. The light guide 11 is held bythe light guide supporting groove 22 at a certain mounting angle withrespect to the frame 20. Accordingly, in the state where the LED module30 and the light guide 11 are mounted in the frame 20, the LED moduleand the light guide 11 are disposed always maintaining prescribedrelative positions via the frame 20. That is, the LEDs 33 r, 33 g and 33b of the LED module 30 can accurately be disposed at positions facing tothe light incident surface 11 a of the light guide 11.

Next, a method of assembling the CIS unit 5 configured as describedabove will be described.

First, the rod lens array 12 is inserted into the lens insertion groove21 from above. The rod lens array 12 inserted into the lens insertiongroove 21 is fixed at a prescribed position by means of adhesive appliedon the lens insertion groove 21.

The light guide 11 is inserted into the light guide supporting groove 22from above. At this time, the holding overhang 22 b holds, from above,the light guide 11 inserted into the light guide supporting groove 22.As described above, the light guide supporting groove 22 has thesectional shape substantially identical to the part of the sectionalshape of the light guide 11. Accordingly, in the state where the lightguide 11 is held in the light guide supporting groove 22, the lightguide 11 is positioned in the light guide supporting groove 22 at theprescribed mounting angle. The convex longitudinal positioning section11 d of the light guide 11 is fitted into the concave longitudinalpositioning section 22 c of the light guide supporting groove 22,thereby allowing the light guide 11 to be positioned with respect to thelongitudinal direction of the light guide supporting groove 22.

Next, the frame 20 is turned upside down such that the substrateinstallation part 23 turns up. In a state where the LED module 30 isturned upside down such that the lead terminals 38 turn up and the mainbody 31 turns down, the LED module 30 is inserted down into the lightsource insertion groove 25 from above. A direction in which the LEDmodule 30 is inserted is orthogonal to both the main and sub-scanningdirections of the CIS unit 5. At this time, the LED module 30 isinserted while the convex positioning section 35 of the LED module 30 ispositioned with respect to the concave positioning section 26 of thelight source insertion groove 25. In this embodiment, the LED module 30is firmly held in a wide space outside the frame 20. Accordingly, theconvex positioning section 35 and the concave positioning section 26 canbe easily positioned.

Insertion of the LED module 30 into the light source insertion groove 25fits the concave positioning section 26 into the convex positioningsection 35, thereby allowing the LED module 30 to be positioned withrespect to the width direction of the light source insertion groove 25.That is, the concave positioning section 26 and the convex positioningsection 35 are thus formed along the insertion direction in which theLED module 30 is inserted into the light source insertion groove 25;when the LED module 30 is inserted into the light source insertiongroove 25, the LED module 30 is positioned with respect to the widthdirection of the light source insertion groove 25. The insertionpositioning surface 37 of the LED module 30 comes into contact with theinsertion positioning section of the frame 20, thereby allowing the LEDmodule to be positioned with respect to the insertion direction of thelight source insertion groove 25. Thus, only the operation of insertingthe LED module into the light source insertion groove 25 allows the LEDmodule 30 to be positioned. Accordingly, the LED module 30 can easily beattached. The concave positioning section 26 is formed along the entirelength of the light source insertion groove 25 in the verticaldirection, and the convex positioning section 35 is formed along theentire length of the main body 31 in the vertical direction.Accordingly, the concave positioning section 26 is fitted to the convexpositioning section 35 over a long extent in the vertical direction.This can prevent loose fit between the LED module 30 and the lightsource insertion groove 25.

Next, the sensor substrate 14 is installed to the substrate installationpart 23. At this time, the lead terminals 38 of the LED module 30 becomein a state of penetrating respective holes 15 (see FIG. 4) provided atthe sensor substrate 14. The lead terminals 38 are soldered in therespective holes 15. Protrusions, not shown, formed apart from eachother on the opening periphery of the substrate installation part 23 aresubsequently welded to the periphery of the sensor substrate 14 by meansof heat swaging, and the assemblage of the CIS unit 5 is completed.

FIG. 7 shows the CIS unit 5 in a state where the rod lens array 12, thelight guide 11 and the LED module 30 are assembled to the frame 20. Inthe CIS unit 5 attached as shown in FIG. 7, the LED module 30 ispositioned with respect to the frame 20, and the light guide 11 is alsopositioned with respect to the frame 20. Accordingly, the LED module 30and the light guide 11 are disposed maintaining prescribed relativepositions via the frame 20. Accordingly, the LEDs 33 r, 33 g and 33 b ofthe LED module 30 can accurately be disposed at the position facing tothe light incident surface 11 a of the light guide 11, and the lightejecting surface 11 b of the light guide 11 can eject light having adesired illumination intensity. Further, the light source insertiongroove 25 is formed to penetrate the frame 20 in the vertical direction.This enables the heat radiation of the LED module 30 to be improved;even in a case of requiring replacement of the LED module 30, thisallows the LED module 30 to be replaced from above by removing only theinsertion positioning section 27 using a tool without detaching thewelded sensor substrate 14.

By the way, in the CIS unit 5, there are cases of changing the size ofthe light incident surface 11 a of the light guide 11 and changing themounting angle of the light guide 11 to the frame 20 according tospecifications. In these cases, it is suffice to newly prepare only aframe 20 where the sectional shape of the light guide supporting groove22 is changed so as to match a changed light guide or a desired mountingangle. That is, in this embodiment, the LED module 30 and the lightguide 11 are positioned via the frame 20. Accordingly, it is suffice tonewly prepare only the frame 20 causing the LEDs 33 r, 33 g and 33 b ofthe LED module 30 to be disposed at a position facing to the lightincident surface 11 a of the light guide 11. This negates the need tonewly prepare an LED module 30 corresponding to the light guide 11,thereby allowing management and production costs to be reduced.

Second Embodiment

Next, configurational elements of a CIS unit 5 of a second embodimentwill be described with reference to FIGS. 8A to 9. FIG. 8A is a diagramof a light source 10 of the second embodiment. FIG. 8B is a perspectiveview of the light source 10 of the second embodiment. FIG. 9 is aperspective view showing a state where the CIS unit 5 of the secondembodiment is assembled. In the first embodiment, the convex positioningsection 35 is formed at the LED module 30, and the concave positioningsection 26 is formed in the light source insertion groove 25. In thesecond embodiment, the convex and concave parts are reversed, and aconcave positioning section 39 is formed at the LED module 30, and aconvex positioning section 28 is formed at the light source insertiongroove 25. Other configuration and attachment methods are analogous tothose of the first embodiment. Identical symbols are assigned theretoand their description is omitted.

As shown in FIGS. 8A and 8B, in the LED module 30 of this embodiment,the concave positioning section is formed linearly along the entirelength of the main body 31 in the vertical direction into a shape cut byone stage from the back surface 34, on the back surface 34 opposite tothe light emitting surface 32 of the main body 31.

As shown in FIG. 9, the convex positioning section 28, which correspondsto the concave positioning section 39 formed on the back surface 34 ofthe LED module 30, is formed in the light source insertion groove 25.The convex positioning section is formed linearly along the entirelength of the light source insertion groove 25 in the verticaldirection.

Accordingly, in a state where the LED module 30 is mounted on the lightsource insertion groove 25, the concave positioning section 39 and theconvex positioning section 28 position the LED module 30 with respect tothe width direction of the light source insertion groove 25. Further, inthis embodiment, the concave positioning section 39 is formed on theback surface 34 of the LED module 30. Accordingly, there is a part wherethe main body 31 is thin. This allows the heat radiation of the LEDs 33r, 33 g and 33 b to be improved. The provision of the concavepositioning section 39 allows the amount of use of sealing resin usedfor the LED module 30 is reduced, thereby allowing the manufacturingcost to be reduced. The LEDs 33 r, 33 g and 33 b and the concavepositioning section 39 may overlap in the thickness direction of themain body 31. In this case, the heat radiation of the LEDs 33 r, 33 gand 33 b can be further improved.

The present invention has been described above along with the variousembodiments. However, the present invention is not limited to theseembodiments. Instead, modifications may be made in an extent of thepresent invention.

The image sensor unit of the present invention is effectively used as animage reading apparatus in, such as an image scanner, a facsimile and acopier.

According to the present invention, the light source can accurately bepositioned with respect to the light guide and easily attached.

What is claimed is:
 1. An image sensor unit comprising: a light sourceincluding a light emitting element on a light emitting surface; a lightguide having a light incident surface and a light ejecting surface, thelight incident surface being positioned facing the light emittingsurface, wherein the light guide emits the light from the light ejectingsurface and illuminates an object to be illuminated; an imaging elementthat images the light reflected from the illuminated object; a sensorsubstrate on which a photoelectric conversion element is mounted,wherein the photoelectric conversion element converts the reflectedlight imaged by the imaging element into an electric signal; and a framethat supports the light source, the light guide, the imaging element,and the sensor substrate, wherein the light source includes a firstpositioning sections disposed on an opposite side of the light emittingsurface of the light source, wherein the frame includes a secondpositioning section disposed on a side facing the opposite side of thelight emitting surface of the light source, wherein the first and secondpositioning sections are complementarily configured to fit together, andwherein the light source is disposed adjacent to one longitudinal end ofthe light guide so that the light emitting surface faces the lightincident surface.
 2. The image sensor unit according to claim 1, whereinthe first and second position sections are formed along an insertiondirection in which the light source is inserted into the frame.
 3. Theimage sensor unit according to claim 2, wherein the insertion directionis a direction orthogonal to a main scanning direction and asub-scanning direction in the image sensor unit.
 4. The image sensorunit according to claim 1, wherein the light emitting surface is flatlyformed.
 5. The image sensor unit according to claim 1, wherein: thelight guide has a third positioning sections disposed at an end of thelight guide on a side of the light incident surface, and the frame has afourth positioning section disposed adjacent at where the light sourceis positioned.
 6. An image reading apparatus comprising: an image sensorunit; and a driving device that moves the image sensor unit, wherein theimage sensor unit comprises: a light source including a light emittingelement on a light emitting surface; a light guide having a lightincident surface and a light ejecting surface, the light incidentsurface being positioned facing the light emitting surface, wherein thelight guide emits the light from the light ejecting surface andilluminates an object to be illuminated; an imaging element that imagesthe light reflected from the illuminated object; a sensor substrate onwhich a photoelectric conversion element is mounted, wherein thephotoelectric conversion element converts the reflected light imaged bythe imaging element into an electric signal; and a frame that supportsthe light source, the light guide, the imaging element, and the sensorsubstrate, wherein the light source includes a first positioningsections disposed on an opposite side of the light emitting surface ofthe light source, wherein the frame includes a second positioningsection disposed on a side facing the opposite side of the lightemitting surface of the light source, wherein the first and secondpositioning sections are complementarily configured to fit together, andwherein the light source is disposed adjacent to one longitudinal end ofthe light guide so that the light emitting surface faces the lightincident surface.
 7. An image sensor unit comprising: a light source,including a light emitting element on a light emitting surface thereof,that illuminates an object to be illuminated; an imaging element thatimages the light reflected from the illuminated object; a sensorsubstrate on which a photoelectric conversion element is mounted,wherein the photoelectric conversion element converts the reflectedlight imaged by the imaging element into an electric signal; and a framethat supports the light source, the imaging element, and the sensorsubstrate, wherein the light source includes a first positioning sectiondisposed on an opposite side of the light emitting surface of the lightsource, wherein the frame includes a second positioning section disposedon a side facing the opposite side of the light emitting surface of thelight source, and wherein the first and second positioning sections arecomplementarily configured to fit together.
 8. The image sensor unitaccording to claim 7, wherein the first and second position sections areformed along an insertion direction in which the light source isinserted into the frame.
 9. The image sensor unit according to claim 8,wherein the insertion direction is a direction orthogonal to a mainscanning direction and a sub-scanning direction in the image sensorunit.
 10. The image sensor unit according to claim 7, wherein the lightemitting surface is flatly formed.